The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Vehicles employ powertrain systems to generate tractive torque for vehicle propulsion. Powertrain systems may transmit torque originating from multiple torque generative devices, e.g., an engine and one or more non-combustion torque machines, through a transmission device to an output member coupled to a driveline. Control systems for operating such powertrain systems operate the torque-generative devices and apply torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, driveability, and other factors. The non-combustion torque machines may include electric machines that are operative as motors or generators to provide a torque input to the transmission independently of a torque input from the internal combustion engine. The torque machines transform vehicle kinetic energy, transferred through the vehicle driveline, to electrical energy that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange among the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed.